docs: Add attribute ondemand to detailinfo

Author: Chris Gårdenberg

new_website/docs/shortcodes.md

@@ -115,6 +115,7 @@ This shortcode is used when you want to create your own custom template [**detai
 | courseinquiryurl          |                boolean               |      null     |
 | order                     | string (`ASC`, `DESC`) |     _null_    |
 | orderby                   |                string                |     _null_    |
+| ondemand | boolean | false |
 
 We will go into each attribute on the [_custom template_](custom-template.md) page.